From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from www62.your-server.de (www62.your-server.de [213.133.104.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3619B49480B for ; Thu, 6 Aug 2026 20:10:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.133.104.62 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047055; cv=none; b=HgI8XBpSzjl6VcfjIlBZm6HIXZK1tXCzOwysFZWpCORaSXGSmnZXmZXDV1AVjdxBp6lzR3XugBNj2mY2ls1mp3uDGT3mUFwxdCCfx29yQGAhFb2vDuLzcb5a0dG0lCy0nNna7C4kr4HAl9TsbX4J6TTqaOocTHQX6Crdq2AUJxQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047055; c=relaxed/simple; bh=xMYMCsOzkScWOPX9Q+ZaRLlk7kPBK39DR/fO/I4SWQo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iyosMbQGHzb6QpWAb4Vu3glhcQzQOuvxyjjSfogmMj0pwwRAzMk5AKa5d7czeoDXwvt1iR+d7v0iSK75/QZWPFf2nQwKMDSznCBSbd8ltjegSZ0sO4yltd1og9jreKtwzsCGV3ZuirbuCdbPJdsu1Z0C76Pv8NtHHuXKo/1GRNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net; spf=pass smtp.mailfrom=iogearbox.net; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b=njGttoZc; arc=none smtp.client-ip=213.133.104.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b="njGttoZc" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=iogearbox.net; s=default2302; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID; bh=cws97ArbMD5eomdnyOIWkONXr3UWpV3ckp/ubJScFts=; b=njGttoZcrJ6r3gQu11950TjN6y Wj4J6an+BGTke2YGw63gu5RkO4SysD1XbcWX13ZoNTdRUKHlPApYtfrOY5P+HpdNqlSXka/CkbWSI c03WrWGtyG0dwgVgnM9uOK/yYDK0W65MzVOMKpqVVInFW2YRNKJxneIkeM4sFk50F79pSN0fiCqSP f48xi9hlQnO8s2TRk+oSCs3dH1eRiC3JfrpuUJySbA9bi1uAGIRfUBIEAzjLInUlpM5Sw5zsRqc7H 3uEUTgsk+6Jq3ms7lTP1CiDI0Q4FAXUtAjL/uXR4SWQ81kDbpS5rQsejXa7kL2dtXretaZ0tANjqm zBxT22wA==; Received: from localhost ([127.0.0.1]) by www62.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96.2) (envelope-from ) id 1ws4QV-000DHZ-14; Thu, 06 Aug 2026 22:10:51 +0200 From: Daniel Borkmann To: memxor@gmail.com Cc: eddyz87@gmail.com, puranjay@kernel.org, info@starlabs.sg, bpf@vger.kernel.org Subject: [PATCH bpf-next v2 6/6] selftests/bpf: Add load-acquire test for probe-memory pointer types Date: Thu, 6 Aug 2026 22:10:47 +0200 Message-ID: <20260806201047.333389-6-daniel@iogearbox.net> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260806201047.333389-1-daniel@iogearbox.net> References: <20260806201047.333389-1-daniel@iogearbox.net> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Virus-Scanned: Clear (ClamAV 1.4.3/28084/Thu Aug 6 08:24:46 2026) Add a verifier test that a BPF_LOAD_ACQ from a rdonly_untrusted_mem pointer (PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED, obtained via bpf_rdonly_cast()) is rejected. Such a source requires BPF_PROBE_MEM fault protection which is not applied to atomic loads; without the verifier fix the load is accepted and would crash the kernel on a fault. # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t verifier_load_acquire [...] #621/1 verifier_load_acquire/load-acquire, 8-bit:OK #621/2 verifier_load_acquire/load-acquire, 8-bit @unpriv:OK #621/3 verifier_load_acquire/load-acquire, 16-bit:OK #621/4 verifier_load_acquire/load-acquire, 16-bit @unpriv:OK #621/5 verifier_load_acquire/load-acquire, 32-bit:OK #621/6 verifier_load_acquire/load-acquire, 32-bit @unpriv:OK #621/7 verifier_load_acquire/load-acquire, 64-bit:OK #621/8 verifier_load_acquire/load-acquire, 64-bit @unpriv:OK [...] #621/19 verifier_load_acquire/load-acquire from rdonly_untrusted_mem pointer:OK #621/20 verifier_load_acquire/load-acquire with invalid register R15:OK #621/21 verifier_load_acquire/load-acquire with invalid register R15 @unpriv:OK #621/22 verifier_load_acquire/load-acquire from pkt pointer:OK #621/23 verifier_load_acquire/load-acquire from flow_keys pointer:OK #621/24 verifier_load_acquire/load-acquire from sock pointer:OK #621 verifier_load_acquire:OK Summary: 1/24 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann --- .../bpf/progs/verifier_load_acquire.c | 28 +++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_load_acquire.c b/tools/testing/selftests/bpf/progs/verifier_load_acquire.c index ae1dab1b0cbb..d17026d7480d 100644 --- a/tools/testing/selftests/bpf/progs/verifier_load_acquire.c +++ b/tools/testing/selftests/bpf/progs/verifier_load_acquire.c @@ -3,6 +3,7 @@ #include #include +#include #include "../../../include/linux/filter.h" #include "bpf_misc.h" @@ -221,6 +222,33 @@ __naked void load_acquire_from_sock_pointer(void) : __clobber_all); } +SEC("socket") +__description("load-acquire from rdonly_untrusted_mem pointer") +__failure __msg("BPF_ATOMIC loads from R{{[0-9]+}} rdonly_untrusted_mem is not allowed") +int load_acquire_from_rdonly_untrusted_mem(void *ctx) +{ + __u64 val = 0; + void *p; + + /* + * bpf_rdonly_cast(x, 0) yields PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED. + * A regular BPF_LDX from it is rewritten to BPF_PROBE_MEM, but a + * load-acquire is not, so it must be rejected, otherwise the JIT emits + * a plain load with no exception table entry and a fault would crash + * the kernel. + */ + p = bpf_rdonly_cast(&val, 0); + asm volatile ( + "r1 = %[p];" + ".8byte %[load_acquire_insn];" // r0 = load_acquire((u64 *)(r1 + 0)); + : + : [p] "r" (p), + __imm_insn(load_acquire_insn, + BPF_ATOMIC_OP(BPF_DW, BPF_LOAD_ACQ, BPF_REG_0, BPF_REG_1, 0)) + : "r0", "r1"); + return 0; +} + SEC("socket") __description("load-acquire with invalid register R15") __failure __failure_unpriv __msg("R15 is invalid") -- 2.43.0